Drug discovery’s dirty little secret?

You may believe that as scientists plumb the depths of the human genome and proteome, the National Institutes of Health budget roars above $30 billion and drug companies spend more money than ever on research and development that the market would be flooded with new drugs.

But as the chart below shows, the number of drugs approved annually by the U.S. Food and Drug Administration has shown a steady decline.

Methodist Hospital Research Institute

Why the stunning drug drought?

One reason, of course, is that it’s incredibly expensive to bring a new drug to market these days.

But that’s not the only reason. It’s striking to me that even as scientists begin to understand the biological underpinnings of disease, they may actually be running out of biological targets for new medicines.

There are about 4,000 approved and experimental drugs out there. But all those drugs, many of which are minor variants of one another, actually only target about 400 gene pathways and other biological areas of interest.

One reason for the limited number of new drugs may be that biomedical scientists are simply running into a wall for new biological targets. According to one estimate, although there are about 30,000 human genes, only about 3,000 of those are “druggable,” that is, genes that can be reached by drugs.

Additionally, only about 3,000 of the human genes are believed to influence disease activity in the body. Since a drug can only be effective if it targets a genetic pathway involved in disease, and it can only be effective if it can actually reach and act upon that pathway, we can see there may indeed be a limited number of biological targets in the body.

Methodist Hospital Research Institute

So what are scientists doing to get around this apparent plateau in new drug discovery? One local computer scientist has an innovative approach that seeks out new uses for old drugs. I’ll have a story on him this weekend, and I’ll update this blog entry when the story’s published.